Study on Bubble Dynamics in Photoelectrochemical Water Splitting with Low-Rate Flow Fields

In this study, we explored the effect of the flow rate on bubble dynamics in photoelectrochemical water splitting using a low-rate rotating flow field. With the flow rate increasing from 0 to 8.4 mm s^-1, the bubble life cycle and the bubble detachment diameter both decrease. However, the mass flow rate of the gas entering the bubble through the “direct injection” mode is not affected by the variation in the flow rate. Different from static conditions, increasing laser power in the flow field will cause the bubble life cycle to first increase and then decrease. In addition, the difference in the dissolved oxygen concentration between the reaction position and the bulk of the liquid phase can be reduced to at most about 1/10 of that under static conditions, which makes it easier for the bubbles to detach. Calculations show that the Marangoni force rather than the lift force remains the important factor affecting bubble departure in a low-rate flow field.